Oh, thank you for letting me know, usually a manga or something comes out before the animated adaptation, so I guess I just assumed. 😅 Sorry about that. I feel as though he had the full story planned out on paper before making the film, but he just had to cut it out of the movie because of the time constraints, so in a sense it was likely left out, making it feel like it wasn't the complete story Makoto Shinkai had originally planned. After its success, however, I feel like he was given the freedom to make the manga as long as it needed to be since the story was so lucrative after the film's debut.